Well that sounds very discouraging. I didn't read your other post, but, I am sure suggestions ranged from putting in a new needle, making absolutely sure it is inserted correctly, bobbin turning in the right direction, inserted correctly, threaded correctly, start off with different bobbin and thread, etc.? since it sews okay on a small sample are you sure you are supporting the quilt itself so there is no drag? Sorry if this has all been recommended and if you have already tried all of this. Also, if it is a computerized or electronic machine, turn off, unplug, wait a minute and restart everything. I hope you can resolve it because it becomes very frustrating, speaking from personal experience. Let us know if any of it works. Good luck.